


A Lesson in Demon Biology

by SpyroForLife



Series: Tomco One-Shots [6]
Category: Star vs. The Forces Of Evil
Genre: Anal Sex, First Time, Grinding, Hand Jobs, M/M, Making Out, Mating Cycles/In Heat, NSFW, One-Shot, Pheromones, Top Tom, bottom marco, tomco - Freeform
Language: English
Status: Completed
Published: 2016-12-18
Updated: 2016-12-18
Packaged: 2018-09-09 10:00:59
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 3,515
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/8886616
Author URL: https://archiveofourown.org/users/SpyroForLife/pseuds/SpyroForLife
Summary: Demons go through heat for about a week out of the year. Marco did not know this, but now he does. And when Tom asks him to help him with it, Marco agrees.





	

Tom looked wary when he answered the call from Marco. “What's up, man?”

“Game night is still on for tomorrow, right?” Marco asked.

Tom stared at him for a moment, one ear flicking. Then realization dawned in his face and he exclaimed, “Oh, crap, game night! I'm sorry, I totally forgot! Listen, um... I feel really bad about this, but tomorrow will not be a good time for me. I didn't realize the date when I agreed, and... yeah. Sorry.”

“That's fine, we can move it. Uh, when will you be available?” Marco could tell something was off about Tom but he couldn't quite put his finger on it.

“Well...” Tom thought about it, then said, “A week from now should be good.”

“Alright, we'll move it to next Saturday. But hey, is something wrong? You look kinda... feverish.” Now that Marco was really looking, he could see that Tom was sweating a little, lines around his eyes.

“Hm?” Tom dragged the back of his hand across his face. “Oh, I'm fine. Just that time of the year, you know.”

“What?”

Tom tilted his head. “Didn't you take sex ed?”

This was an unexpected change in topic but they've had more awkward talks. Marco shrugged. “Well I mean, in ninth grade we somewhat went over it in health class, but... it was pretty terrible. They basically just drilled 'don't have sex' into our heads, and also 'but if you do, not that you should! But if you _do_ , use a condom.' And then they warned us about STDs and babies. They somewhat told us about the actual body parts involved. It wasn't very helpful to be honest.”

“Oh. So they didn't talk to you about heat? Or do humans not do that?”

“No. We don't go into heat, humans can reproduce any time of the year.”

“So can we, but there's still one week where the urge to reproduce overwhelms us. Like, it's the best time of the year to get pregnant so conditions are perfect at birth. Kinda useless now since we're a civilized species and can raise our children in any season but it's still a drive that we have. So uh... it starts with puberty and this is like, my second year having to deal with it so I'd really prefer to be alone until it wears off.”

“Is there no way to... I don't know, dampen the mood?”

Tom chuckled. “Well, there are drugs that can lower one's libido. Being alone also helps. And of course there's just having sex with someone, but I don't really like anyone enough to do that. I'll be fine, it's basically a holiday for most of us, I can just lock myself in my room and no one will bother me. I've got enough stuff to entertain myself with.” He waggled his brows.

“Dude, too much information.”

“You're lucky you don't have to deal with this, you know. I kinda envy you.”

“Well, good luck with that.”

“Thanks. I'll talk to you later, okay?”

“Yeah.” Marco said goodbye and hung up. He considered the conversation they just had, then shook his head, setting his phone down and looking back at his computer. It seemed he was always learning something new and kinda weird about demons. Tom hadn't even mentioned this last year. Then again, they weren't hanging out as much then.

He wrote a quick note about the date so he could avoid bothering Tom at this time next year, and settled into playing his game. He supposed he could wait a week before talking to his friend again.

 

A ringing sound woke Marco up. He groaned and felt around on his bedside table for his phone, picking it up. The first thing he looked at was the time. 3:13 AM. Then he looked down at the part that said Tom was requesting to Facetime with him. He sighed and tapped the button to answer it. “Yeah?”

Tom's face appeared on screen. He seemed breathless. “Hey. Sorry to bother you...”

“Dude, it's 3 AM.”

“I know, I know, just... wanted to talk to you for a bit.”

Marco raised a brow. “You sure? I mean just last night you were telling me you wanted to be alone.”

“I know, but I changed my mind. I really just need someone to talk to right now.”

“Well... can it wait until morning? I was kinda in the middle of sleeping...”

Tom bit his lip, looking him over. He seemed distracted. “Y-yeah, okay. I can call back later.”

“Are you okay?” Marco looked more closely at him. “You're kinda shaking. And sweating a lot.”

“Just the heat. Makes me really anxious. But... looking at you helps. It... really helps.” Tom licked his lips, and Marco flushed.

“Okay, I'll call you in the morning,” Marco started to say, but Tom interrupted him, eyes widening.

“Wait! Okay, look, this is... The real reason I'm calling...” Tom swallowed, then said, “I need your help. Please, last year was awful. And this one is already shaping up to be worse. I... want to sleep with you.”

Marco nearly dropped his phone. “You... want to _what_?”

“It doesn't have to mean anything,” Tom insisted. “Just... you're the only one I really like enough to do this, and it'll make me feel a whole lot better.”

Marco had no idea how to respond. His cheeks grew hot. “This is... really sudden, and weird, I'm not sure...”

“Of course I don't want you to do anything that'll make you uncomfortable, I just figured I'd ask.”

Marco rubbed his eyes, and sighed, pushing himself up. Sleeping with Tom wasn't an unappealing idea at all. But he's never quite figured out how to address even going out with him, let alone having sex with him. But now Tom was offering, and he seemed pretty desperate. “If I come over, do you promise not to bother me again with this in the middle of the night?”

“Absolutely,” Tom said earnestly. “I wouldn't have called but I was actually woken up by how uncomfortable I am, I just wanted to see you, maybe rub out a quick one, but actually talking to you has made me want so much more than to see you. So you're coming over?”

“Yeah. Guess I am.”

Tom abruptly hung up. Marco stared at his phone for a moment, then turned to see fire flaring up next to his bed, a portal opening. He got up and hopped through it, and immediately came face to face with Tom, who was on his knees on his bed, staring at him. Now that Marco was directly in front of him, he could see how his pupils were dilated, and Tom's chest was heaving as he panted. Marco glanced down in time to see Tom hastily move his hand away from the front of his boxers, which were the only thing he slept in.

Marco's face heated up. “Were you jerking off while talking to me?”

“M-maybe a little.” Tom didn't seem ashamed of it. He was more excited than anything. “But now you're here!”

“Yeah. I'm here.” Marco could tell the other had gotten himself very worked up. His hair was messy, face flushed. He could smell sweat. Though there was another scent present too, something spicy and enticing. He inhaled, leaning forward a bit. “You're not very subtle.”

“I know. Oh man, you have no idea how horrible this is. But it's okay. I feel like if you help me, I'll feel better.”

Marco really should be more nervous about this, but he found that he wasn't. He trusted Tom and found him attractive. Especially with how he was looking at him now, hunger in his red eyes, fingers clenching as he fought the urge to reach out to him. Not to mention, that strange scent was quite relaxing. He stepped forward. “Does masturbating not help?”

“Hardly.” Tom finally reached out, and Marco took his hand. Tom pulled it close to his face, nuzzling and burying his nose against his wrist. His shoulders shook. “It just makes me want more. And... thinking about you, looking at you... well, it just made me want you in particular.”

“I'm glad heat isn't something humans have to deal with.” Marco swallowed when Tom trailed his lips up his arm. It was surprisingly tender, and his stomach fluttered.

“Lucky bastard.” Tom reached his shoulder, and gazed up at him. His heated expression made Marco feel exposed. “But humans have enough sex as it is. Y'all don't need a mating season on top of that.”

“True.”

Tom looked him over, then tugged him forward. Marco climbed onto the bed with him, and Tom laid back, guiding Marco to sit on his hips. “I don't want to push you into anything. What do you want to do?”

Marco examined him. He had to admit, Tom looked really good under him. He memorized how he looked with that sheen of sweat on his skin, chest moving up and down with heavy breaths, his blown pupils and the way he kept chewing on his lower lip. He set his hand on Tom's chest and heard his breath hitch. His skin was even hotter than usual.

Marco ran his fingers down, feeling over the other's muscles. Tom squirmed against the pillows he was propped up on, hands settling on Marco's waist. He rubbed his thumbs in circles against his hip bones, and Marco exhaled, leaning forward. He could feel Tom's erection under his butt, and smiled at how frustrated the demon was. “You're kinda cute like this.”

“Marco, please don't tease me,” Tom whined.

“Heh, sorry.” Marco was only wearing pajama pants right now. He decided to let Tom know, rubbing against his crotch. “You know... I'm not wearing underwear right now. Just these.”

Tom's eyes widened slightly, pupils growing rounder. “Marco...”

“It's more comfortable. Worked out nicely, hm?” Marco was enjoying teasing the other. But he didn't want to mess with him too much. He straightened up, taking hold of his waistband. “You said you had stuff here to entertain yourself with?”

“Y-yeah!” Tom pushed himself up, reaching over to the table next to his bed. “I have lube, we'll want that, and... and I have toys, dildos mostly, and a vibrator...”

“Get the lube.”

“Sure!” Tom grabbed a bottle, and Marco ran his hand through Tom's hair.

“You're being pretty cooperative,” he commented.

“Well, you know. I'm in heat, I want to have sex, you're offering to have sex with me. Of course I am.” Tom looked at him, offering the bottle.

“Just hold onto that for a moment.” Marco pulled his pants down. Tom immediately dropped his gaze to watch, and Marco briefly felt embarrassed. But Tom was being respectful and he soon felt comfortable again, dropping his pants over the side of the bed. He casually crossed his arms in front of his body, covering himself with his wrists. “Take a picture, it'll last you longer.”

Tom looked back up at his face. “Don't tempt me. I would love to take a picture of you.” He glanced at where his phone had been discarded, ears lifting a bit. “Actually, can I? Please?”

“Depends. Are you going to send it to anyone?”

“No. No, this will be just for me to enjoy.”

“Then go ahead.”

Tom picked up his phone, and Marco did his best to look appealing and sexy as he took a picture. When Tom kept the phone up for a few more moments, Marco tilted his head and lowered his eyelids, biting his lip. Tom's hands shook, and he quickly snapped another pic. “You look so good.”

Marco had to admit, Tom's admiration was flattering. He wondered if it was just because he was in heat, or if he really felt this way about him. He'll have to talk to him about it once they were done. As it was, he felt attractive and important, and he finally moved his hands away from his groin so Tom could see him better. He wasn't quite erected yet, but he was getting there.

Tom took one final picture, then put his phone down. He leaned forward, draping an arm around Marco's neck and smiling at him. Their faces were inches apart. Understanding what he wanted, Marco set his hands on his waist and leaned in for a kiss. The first meeting of their lips was clumsy, messy. Their noses bumped together and Marco backed off first, shaking his head and laughing. Tom laughed too, and they tried again. This time they fit together nicely, and Tom moaned at his taste, lips parting. Marco shivered, following his lead as they made out.

Marco slid his hands around to Tom's back, nails digging in. The demon rocked his hips against him, his clothed erection rubbing against Marco's bare skin, and the friction made him groan.

“Aah, Marco... please...” Tom whispered against his lips, hands slipping around to grip the back of Marco's neck, fingers fisting into his hair. He was firmly rutting into him now. “More...”

“What do you want?” Marco replied softly.

“Wanna fuck you, please...”

“Geeze, you're horny. Okay, yes, whatever you need to do.”

Tom leaned his head back, searching Marco's face. “Anything I want?”

“Yeah. I trust you.”

Tom dropped his mouth to Marco's neck, nibbling on the sensitive skin. He gasped, cock jerking, and next thing he knew, Tom's hand was on it, fingers wrapping around and stroking.

“Oh _fuck_ , Tom...” Marco nearly thrust against him, his hand was so hot, but his palm was soft, and the conflicting pleasure and pain got him hard.

“You taste so good,” Tom murmured into the crook of his neck. “I can smell your lust.”

“Mm, I can smell yours. I think.”

Tom chuckled. “Your sense of smell isn't near as good as mine. But we do put out pretty strong pheromones during this time of year. That's what I was taught.”

“Whatever it is, you smell good.”

“Thank you.” Tom kept pumping his hand up and down Marco's length, suckling on his throat. His free hand went to his own hip, easing his boxers down. “Lift up a bit.”

Marco listened, getting up on his knees, and Tom pulled his underwear off. He had to let go of Marco for a few moments, but once they were thrown aside, he pulled Marco back onto his lap, so they were skin to skin.

“Ah...” Marco was breaking out into a sweat now, and he pressed himself to Tom's front, arms around his neck. He was getting more into this than he had expected when he first came over. He tried to tell the other through his body language that he could do whatever he wanted to him.

Tom responded, kissing him and rolling them over so Marco was pinned underneath him. They hardly separated, making out desperately, Tom growling low in his throat while Marco let out soft huffs and whines every time he leaned back to breathe. Tom used the distraction to coat his fingers with lube, beginning to loosen Marco. He was a bit too rough in his haste, trying to fit in two fingers too soon, causing Marco to grunt and slap his back.

“Sorry,” Tom apologized through clenched teeth. “I just... really want you.”

“I can tell.” Marco's head was swimming, but he could still focus enough to know Tom needed to slow down a bit.

Tom was slightly more gentle as he continued, but it still wasn't long before he was working in his third finger. A little more lube, and he even teased in a fourth.

“Nngh, fuck...” Marco squeezed his eyes shut, shaking.

“You okay?” Tom asked.

“Y-yeah, fine. I'm good.” Marco was able to ignore the discomfort, just gazing into Tom's half-lidded eyes, fingers running through his hair.

“Alright.” Tom pressed in deep, stroking over Marco's sweet spot. He loved how it made Marco jump and gasp out, before clutching him tighter, wanting to feel it again. When Tom was sure that he was relaxed enough, he slid his fingers out. He thought to himself that he could hardly believe this was happening. He had Marco in bed with him, about to have sex with him. If it weren't for heat, he probably never would have asked for this. Yet he also wondered why he hadn't asked him sooner. Marco was willing and this was a lot of fun. Hopefully he wanted to do it again. Now that Tom's had this small taste of him, he wasn't sure he'd be able to give it up.

Tom coated his length with lube and set the bottle aside. He settled between Marco's legs, pressing his tip to his hole. He was so hard it almost hurt, but he still took a moment to just take in the sight. Marco looked good sprawled out beneath him, dark eyes looking up at him, mouth slightly open. Tom softly kissed his swollen lips, and felt Marco's hands run up into his hair.

“Can I?” Tom asked.

Marco nodded, whimpering.

Tom frowned slightly, and kissed the corner of his mouth. “I need to hear you say it. Out loud, I need you to say yes.”

“Yes Tom, I want you, please...”

Marco's voice was so sweet when he was pleading. Tom gave in, sliding into him. Marco grunted, pressing his face to Tom's shoulder. His arms wrapped around Tom's middle, fingers digging into his back.

“Let me know if it hurts,” Tom said.

“Mm...” Marco nodded, and pressed a kiss to his skin.

Tom tried to hold back, but he just couldn't. He needed this far too much. He thrust all the way in, and Marco cried out, arching. He didn't speak though, just tightening his legs around Tom's waist, holding him close. Tom settled into a rhythm, pounding into him hard, thrusting him back and forth. Marco squirmed in his grip, keening with pleasure. His eyes squeezed shut, and he bit into Tom's neck to muffle himself.

“Aah...” Tom closed his own eyes, focusing on the pleasure, one arm sliding under Marco's back to support him, the other bracing on the bed to support himself. He realized he was being too rough, he could tell that Marco was sobbing, felt the tears against his skin. But at no point did Marco tell him to stop, or slow down. The human kept holding on, moaning and rocking his hips to meet him, shouting Tom's name every time they got into sync.

Tom finally registered that Marco was trying to rub his erection against him, and lowered his weight onto it. It was within moments of doing so that Marco came, with a particularly ecstatic cry. His entire body trembled, clenching around Tom, and Tom felt a spray of cum across his stomach. The heat built, pressure building in his gut, and he closed his eyes again, gasping. “Marco...”

“Nn, Tom... Tom, you're so hot, aah...”

Tom leaned more onto him, wanting to feel as much of him as possible. “Ah, Marco, can... can I go faster?”

“Y-yeah...”

“Let me know if it's too much.”

“I can handle it.”

Tom nuzzled him, and sped up. It only took him about another minute, and when Marco's nails scraped down his back, it was the last push he needed to get over his edge. He bottomed out, finishing deep inside the other.

“Aah, hot!” Marco jerked, and Tom actually yelped at how sharply he clawed at him, feeling the desperation in Marco's hands. He quickly pulled out, staring at him.

“You okay?”

Marco pushed himself up, eyes watering. He groaned, rubbing his eyes. “Y-yeah. Your cum is really hot. But... it cooled down. Man.” He shifted his legs, then sighed, flopping back.

Tom slowly laid down on him, brushing his hair back. “As long as you're okay.”

Marco smiled, looking at him with clear affection. “I'm fine. How about you?”

Tom considered how he felt, then said, “Well, my head is definitely a lot clearer now. I feel good.”

“That's good.” Marco yawned, eyes falling shut. “Now, if you don't mind... I have sleep to get back to.”

“Alright. Want me to move?”

“Nah. I'm pretty comfortable right here.” Marco rested his arms around him, already drifting off.

Tom rested his chin on his chest, watching him. “Okay. Let me know if you need anything.”

“Mhm...”

Soon Marco was asleep, leaving Tom to just reflect on what they had done. He was glad Marco had agreed to help him out. He felt a lot better now. The heat had pretty much left his body, leaving behind a satisfied warmth. He wondered how long it would last.

“Goodnight,” Tom said quietly, closing his own eyes. He was looking forward to seeing what the morning would bring, once they've both had time to think all this over. If his heat was over early due to this, he would be fine with that. And if not... perhaps Marco would like to go again. Either way, he was just happy to be with him.


End file.
